Sperm cryopreservation is a process whereby sperm are generally stored frozen at -196°C in a tank filled with liquid nitrogen (LN2) and a standard practice used in infertility treatment. However, the LN2 freezing method can be regarded as a fragile preservation approach. Development of an alternative storage method that can permit storage at room temperature and does not require periodic replenishment of a freezing agent is necessary. An alternate storage method that is attracting attention is the lyophilization (freeze-drying) method, although the lyophilization method has not yet been clinically applied to humans. We introduce a new freeze-drying method (micropowder-dry) that may control the formation of ice crystals in cells.